JPH0476232A - Flame failure predicting determiner for gas turbine engine - Google Patents

Abstract

PURPOSE:To predictably determine generation of failure with high accuracy by predictably determining the generation of failure on the basis of an air-fuel ratio and flame fluctuation information determined by a power spectrum. CONSTITUTION:There is provided a flame detector A for detecting light generated from flame inside a combustor in a gas turbine engine. A frequency analyzer B frequency-analyzes a signal output from the flame detector A to determine a power spectrum. A flame fluctuation calculator C calculates flame fluctuation information corresponding to the fluctuation of flame on the basis of the power spectrum determined by the frequency analyzer B. A flame predicting determiner D predictably determines flame on the basis of an air-fuel ratio output from an air-fuel ratio detector E and the flame fluctuation information output from the flame fluctuation calculator C. Therefore, it is possible to predictably determine the flame of the combustor with high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flame extinction prediction and determination device for a gas turbine engine.
In particular, the present invention relates to a flame extinction prediction and determination device that predicts and determines flame extinction in a combustor of a gas turbine engine equipped with a heat exchanger.

[Prior art and problems to be solved by the invention] A conventional fuel supply system for a gas turbine engine is disclosed in Japanese Patent Application Laid-Open No. 50-312.
It is described in Publication No. 11. This fuel supply system responds to the deviation between the electrical signal corresponding to the actual engine speed and the electrical signal corresponding to the desired engine speed to prevent flame-out and stalling of the gas turbine engine. A lower limit value for the amount of fuel to be supplied is set. Further, in British Patent No. 946111, upper and lower limits of the fuel supply amount are set in order to prevent flame-out and stall of the gas turbine engine. These upper and lower limits are the intake air temperature T
and the engine speed Na, or by further adding the compressor pressure P of the combustor population. The reason for using the intake air temperature T is to take into account the temperature state of the atmosphere.During steady operation, the temperature of the air at outside temperature rises due to the compression of the compressor, and the intake air temperature T of the combustor population is at its maximum. The temperature will be around 400℃.

However, the above-mentioned conventional gas turbine engine is a gas turbine engine that does not use a heat exchanger to heat the air.
While the temperature change of the air supplied to the combustor is relatively small, automotive gas turbine engines have a heat exchanger upstream of the combustor that further heats the compressed air and supplies it to the combustor. Because of this, the air temperature at the combustor inlet changes significantly. Therefore, the flammability limit is completely different compared to a gas turbine engine without a heat exchanger. In other words, since the air temperature at the combustor inlet does not correspond to the engine speed and varies greatly depending on the conditions, for example, when decelerating from high-speed, high-load operation to idle, the flammability limit is on the fuel deceleration line. The flame will blow out and extinction will occur. Therefore, it is important to accurately predict and determine the extinction of inflammation.

Accordingly, an object of the present invention is to provide a flame-out prediction/determination device for a gas turbine engine that can accurately predict and determine flame-out in a combustor.

Japanese Unexamined Patent Publication No. 63-306310 related to the present invention discloses that an optical power signal is detected from a flame in a combustor, the optical power signal is frequency-analyzed to obtain a power spectrum, and this power spectrum is utilized. A technique for detecting a combustion state and controlling the combustion state to an optimal combustion state has been disclosed.

Although this technique makes it possible to optimally control the combustion state, it is not possible to accurately predict and determine flame extinction, which is the objective of the present invention.

[The island's means of solving problems]

In order to achieve the above object, the flame extinction prediction and discrimination device for a gas turbine engine of the present invention includes a flame detection means for detecting light generated from a flame in a combustor, and a frequency analysis of a signal output from the flame detection means. a frequency analysis means for calculating a power spectrum based on the power spectrum; a flame fluctuation calculation means for calculating flame fluctuation information corresponding to the fluctuation of the flame from the power spectrum; an air-fuel ratio detection means for detecting an air-fuel ratio; and an extinguishing prediction determination means for predicting and determining the occurrence of extinguishing based on the fluctuation information.

[Effect]

The flame detection means of the present invention detects light generated from the flame within the combustor. The frequency analysis means frequency-analyzes the signal output from the flame detection means to obtain a power spectrum. The flame fluctuation calculation means calculates flame fluctuation information corresponding to flame fluctuation from the power spectrum obtained by the frequency analysis means. The air-fuel ratio detection means detects an air-fuel ratio determined from the amount of intake air and the amount of fuel supplied to the combustor, or detects the air-fuel ratio of exhaust gas. The flame-out prediction determination means predicts and determines flame-out based on the air-fuel ratio outputted from the air-fuel ratio detection means and the flame fluctuation information outputted from the flame fluctuation calculation means. According to experiments conducted by the present inventors, combustor flame extinction tends to occur in a region where the air-fuel ratio is equal to or higher than a predetermined value, and flame fluctuation information changes in a monotonous function of the air-fuel ratio in a region where flame extinction tends to occur.

Therefore, it is possible to predict and determine flame extinction with high accuracy based on the air-fuel ratio and flame fluctuation information.

In predicting and determining the occurrence of flame extinction, as shown in Fig. 1, it is necessary to manually input the signal output from the flame detection means to the frequency analysis means based on the air-fuel ratio determined from the air flow rate and the fuel supply amount. The power spectrum may be obtained from the manually generated signal using a frequency analysis means. At this time, the flame fluctuation calculation means calculates flame fluctuation information from the power spectrum, and the flame fluctuation determination means determines the magnitude of the flame fluctuation information, thereby predicting and determining the occurrence of flame extinction. In this way, it is possible to predict and determine the occurrence of flame extinction based only on the signal output from the flame detection means in a region determined based on the air-fuel ratio and where flame extinction is likely to occur.

Further, as shown in FIG. 2, the air-fuel ratio is calculated by the air-fuel ratio calculation means, and the flame fluctuation information is calculated from the power spectrum obtained by the frequency analysis means by the flame fluctuation calculation means,
The occurrence of flame extinction may be predicted and determined based on this air-fuel ratio and flame fluctuation information. In this way, it is possible to predict and determine the occurrence of flame extinction based on the magnitude of the air-fuel ratio and the magnitude of flame fluctuation information.

[Effects of the Invention] As explained above, according to the present invention, the occurrence of extinguishing is predicted and determined from the air-fuel ratio and the flame fluctuation information obtained from the power spectrum, so the occurrence of extinguishing can be accurately predicted and determined. You can get the effect that you can.

〔Example〕

A first embodiment of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 3, a compressor 30 for compressing air is connected to a turbine 32 driven by combustion gases. In addition, the output shaft 3 corresponds to the turbine 32.
A power turbine 34 with 6 is arranged. A combustor 38 is arranged to supply combustion gas to the turbine 32, and on the upstream side of the combustor 38, air heated by the compressor 30 is heated by the combustion gas supplied via the turbine 32 and the turbine 34. A heat exchanger 42 for heating is arranged.

As shown in FIG. 4, the combustor 38 includes a bottomed cylindrical casing 10 and a bottomed cylindrical liner 12 housed within the casing 10 such that a space is formed between the casing 10 and the casing 10. We are prepared. A fuel injection valve 16 is attached to penetrate the bottom surface of the casing 10. Also, liner 1
A swirler 14 for mixing primary air and fuel is attached to the bottom of the fuel injection valve 2, and this swirler 14 is connected to a fuel injection port of a fuel injection valve 16. A plurality of circular secondary air introduction ports 18 for introducing secondary air into the liner 12 are bored at predetermined intervals along the circumferential direction on the side wall surface of the swirler 14 of the liner 12. Further, a plurality of circular dilution air introduction ports 20 for introducing dilution air are bored at predetermined intervals along the circumferential direction on the side wall surface of the combustor outlet 22 of the liner 12. A spark plug 26 is attached so as to penetrate the side wall of the casing 10 and protrude into the liner 12. A flame sensor 70 is provided passing through a portion of the liner 12 near the spark plug 26 . As shown in FIG. 3, this flame sensor 70 includes an optical fiber 70A passing through the liner 12 and an optical fiber 70
It is composed of a light receiving element 70B such as a photodiode or a phototransistor provided at the outer end of the combustion chamber A.

The space formed between the liner 12 and the casing 10 acts as an air passage 24 through which air passes.

According to this combustor, after the air (combustion air) compressed by the compressor 30 is heated by the heat exchanger 42 from the air passage 24 between the casing 10 and the liner 12,
It is supplied to the combustor 38.

This air is supplied into the liner I2 as primary air by the swirler 14, and is also supplied into the liner 12 as secondary air through the secondary air inlet 18 and as dilution air through the dilution air inlet 20. Ru. fuel injection valve 1
The fuel injected from the spark plug 2 is mixed with primary air, which is a swirling flow supplied by the swirler 14.
6 to cause primary combustion. This secondary combustion mixture is subjected to secondary combustion by the secondary air supplied from the secondary air inlet 18, and is diluted by the dilution air supplied from the dilution air inlet 20, so that the average temperature of the combustion gas is lowered to the turbine turbine. At the same time, the temperature distribution of the combustion gas at the combustor outlet 22 is made uniform, and the combustion gas is discharged from the combustor outlet 22. This combustion gas then drives the turbine.

Extinguishing of the combustion gas in the liner 12 occurs when the flame is blown away by the air when the air flow velocity becomes too high compared to the flame propagation velocity in secondary combustion and secondary combustion.

According to an experiment conducted by the present inventors in which compressed and heated air was supplied to the combustor shown in FIG. It varied greatly depending on the temperature Ta of the air at the inlet of the combustor and the pressure Pa of the air at the combustor.

FIG. 8 shows a case where the temperature Ta of the combustor artificial air is 320° C., and as the air pressure Pa increases, the flammable range expands, that is, the extinguishing range decreases. FIG. 9 shows the case where the air pressure Pa is 2 kg/c++f, and as the air temperature Ta increases, the flammable range expands, that is, the flame extinguishing range decreases. however,
The expansion of the flammable range as the air temperature Ta increases is greater than the expansion of the flammable range as the air pressure Pa increases. Therefore, in a gas turbine engine that compresses and heats air, the temperature of the air in the combustor is Ta
(approximately 400° C. to 700° C. during steady operation), air flow rate Ga, etc. must be taken into consideration.

When the present inventors conducted an experiment on extinguishing flame by supplying compressed and heated air to the combustor shown in FIG. 4, the air flow rate Ga and the air temperature Ta were determined.

It has been found that if the minimum fuel supply amount Gfmin is determined based on the air pressure pa, and fuel is supplied in an amount equal to or greater than this minimum fuel supply amount Gfmin, flame extinguishing does not occur.

According to experiments, the optimum value of this minimum fuel supply amount Gfmin was given by the following equation (1).

Gfmin=K l ・P a1/2・Ta ' ・G
a2...-(1) However, K1 is a coefficient.

The coefficient 1 in the above equation (1) is changed to detect flame extinction in the combustor as described below, and to be the fuel supply amount immediately before flame extinction occurs.

Further, the maximum fuel supply amount Gfmax is given by the following equation (2).

Gfmax= (K2-3 ・Ta) ・Ga-
-C2) Here, K2 and K3 are positive constants. This constant 2.K3 can be determined through experiments so that the combustion gas temperature when combusted with the maximum fuel supply amount Gfmax does not exceed the heat resistance limit temperature of the combustor, turbine, etc.

In order to determine this minimum fuel supply amount Gfmin, the population of the combustor 38 is determined based on the air temperature Ta, as shown in FIG.
, a sensor group 40 consisting of a plurality of sensors that respectively detect air pressure Pa and air flow rate Ga is attached. The temperature Ta, pressure Pa, and air flow rate Ga signals detected by the sensor group 40 are used by a Gfmin function generator 52, which generates a signal corresponding to the minimum fuel supply amount Gfmin, and a signal corresponding to the maximum fuel supply amount Gfmax. G to do
The fmax function generator 50 and gate circuit 74 are powered.

The Gfmin function generator 52 is connected to a coefficient 1 calculator 54 that calculates 1 as a coefficient for calculating the minimum fuel supply amount. The output end of the Gfmax function generator 50 is connected to the cathode of the upper limit value diode 56, and the output end of the Gfmin function generator 52 is connected to the anode of the lower limit value diode 58. The Gfmax function generator 50 is
The Gfmin function generator 52 outputs a signal at a level corresponding to the maximum fuel supply amount Gfmax, and the Gfmin function generator 52 outputs a signal at a level corresponding to the maximum fuel supply amount Gfmax.
A signal with a level corresponding to fmin is output. Anode of upper limit value diode 56 and lower limit value diode 5
The cathode of 8 is connected to the output end of a fuel supply amount signal generator 60 that generates a signal at a level corresponding to the fuel supply amount Gf. The output end of the fuel supply amount signal generator 60 is connected to a fuel injection pump 44 with a flow rate regulator connected to the fuel injection valve 16 and a gate circuit 74 . Furthermore, a driver controller 62 that outputs a signal according to the amount of depression of the accelerator pedal 64 is connected to the input end of the fuel supply amount signal generator 60 .

The flame sensor 70 described above is connected to a gate circuit 74. A sensor for detecting the air flow rate in the sensor group 40 and a fuel supply amount signal generator 60 are connected to the gate circuit 74, and a fuel supply amount Gf times signal and an air flow rate Ga signal are manually input.

The gate circuit 74 allows the output signal of the flame sensor 70 to pass when the air-fuel ratio Ga/Gf is equal to or higher than a predetermined value (for example, 200). The gate circuit 74 is connected to a frequency analyzer 76 that calculates the power spectrum. Frequency analyzer 76
is connected to a calculator 78 that calculates flame fluctuation information. The arithmetic unit 78 is connected to a discriminator 80 that discriminates the magnitude of the flame fluctuation information and predicts and discriminates the occurrence of flame extinction. The discriminator 80 is connected to a 1-coefficient calculator 54 that calculates 1 for the coefficient, and the 1-coefficient calculator 54 is connected to the Gfmin function generator 5.
Connected to 2.

The operation of this embodiment will be explained below. The air compressed by the compressor 30 passes through the air passage 46 to the heat exchanger 4.
2 and heated. The air heated by the heat exchanger 42 is supplied to the combustor 38, mixed with fuel injected from the fuel injection valve 16, and combusted as described above. Combustion gas is supplied through combustor 38 and rotates turbine 32 and power turbine 34 before being discharged through heat exchanger 42 .

The G fmax function generator 50 outputs a maximum fuel supply amount signal at a level calculated according to the above equation (2) based on the air temperature Ta detected by the sensor 40 and the flow rate Ga. The Gfmin function generator 52 calculates the minimum fuel supply amount according to the above equation (1) based on the air temperature Ta, pressure Pa, and flow rate Ga detected by the sensor group 40, and sets the level corresponding to the minimum fuel supply amount. Outputs the signal. The fuel supply amount signal generator 60 is connected to the accelerator pedal 64
Generates a fuel supply amount signal according to the amount of depression. When the level of the fuel supply amount signal becomes larger than the level of the maximum fuel supply amount, the potential of the anode of the upper limit diode 56 becomes higher than the potential of the cathode, so the potential between the anode and cathode of the upper limit diode 56 increases. A current flows from the fuel supply amount signal generator 60 toward the Gfmax function generator 50 until the Gfmax function generator 50 becomes equal, thereby limiting the level of the fuel supply amount signal from exceeding the level of the maximum fuel supply amount signal. Additionally, if the level of the fuel supply amount signal falls below the level of the minimum fuel supply amount signal,
Since the potential of the cathode of the lower limit diode 58 becomes lower than the potential of the anode of the lower limit diode 58, adjustment is made from the Gfmin function generator 52 until the potentials of the cathode and anode of the lower limit diode 58 become equal. Current flows in the direction of the fuel injection pump 44, thereby limiting the level of the fuel supply amount signal so that it does not fall below the level of the minimum fuel supply amount signal. The regulator-equipped fuel injection pump 44 controls the fuel injection valve 1 by a fuel supply amount signal whose level is limited to a value within a predetermined range by an upper limit value diode 56 and a lower limit value diode 58.
6 to inject fuel into the liner 12.

When the air-fuel ratio Ga/Gf exceeds a predetermined value, the gate circuit 74 is opened, allowing the output of the flame sensor 70 to pass through. When a flame occurs, the flame sensor 70 detects the light generated from the flame, and this detection signal passes through a gate circuit 74 and is input to a frequency analyzer 76 . Frequency analyzer 76 calculates a power spectrum from the signal output from flame sensor 70.

This power spectrum changes depending on the frequency as shown in FIG. The calculator 78 calculates flame fluctuation information based on the power spectrum calculated by the frequency analyzer 78 according to the following equation.

D-・・・(3) However, A is the integral value of the power spectrum over all frequencies (e.g., 0 to 200 Hz), and B is the integral value of the power spectrum in a specific frequency region (e.g., the region from about 0 to 20 Hz). It is a value. The discriminator 80 predicts and discriminates the occurrence of flame extinction by determining whether the flame fluctuation information is less than or equal to a predetermined value (for example, 90%). As shown in Figure 7, flame extinction occurs in the region where the air-fuel ratio Ga/Gf is 200 or more, and at this time the flame fluctuation information gradually monotonically decreases from the maximum value (approximately 98%). By determining whether the flame fluctuation information is less than or equal to a predetermined value (90%) in a region where the fuel ratio is greater than or equal to a predetermined value, it is possible to accurately predict and determine whether or not the flame is extinguished. In addition, just before flame extinction occurs, the flame fluctuation information monotonically decreases from the maximum value, so the occurrence of flame extinction is predicted and determined by determining whether the flame fluctuation information decreases from the maximum value. It is also possible.

Note that the flame fluctuation information may be determined by the following formula.

D-・・・(4) However, as shown in Figure 6, J is the maximum value of the power spectrum in the entire frequency range, and K is the maximum value of the power spectrum in the specific frequency band (for example, the area from 507 to the maximum frequency). This is the maximum value of the power spectrum.

When using the fire fluctuation information in equation (4) above, the occurrence of flame extinguishment is predicted when the fire fluctuation information is less than a predetermined value (for example, 10%).

When the discriminator 80 predicts and determines the occurrence of extinguishing, the 1-for-coefficient calculator 54 increases 1 for the coefficient by a predetermined value ε every time the occurrence of extinguishment is predicted and determined according to the following formula.

K1-(1+ε)Kl...(5) In addition, if the flame-extinguishing judgment is not made, the level of the minimum fuel supply amount signal can be decreased according to the following formula, and the minimum fuel supply amount may be lower than the optimum value due to an error etc. It is possible to correct the increase in fuel consumption, thereby reducing fuel consumption.

K1-(1-ε)Kl...(6) Moreover, the above-mentioned predictive determination of the occurrence of inflammation may be performed by a microcomputer. Figure 10 shows how to calculate the minimum amount of fuel to be supplied by predicting the occurrence of quenching. This shows a minimum fuel supply amount calculation routine performed by a microcomputer. First, in step 100, the air flow rate Ga,
The fuel supply amount Gf and the output of the flame sensor 70 are taken in, and in step 102, the output of the flame sensor 70 is frequency-analyzed to obtain a power spectrum, and from this power spectrum, flame fluctuation information is obtained according to the above equation (3) or (4). Calculate the difference. In the next step 104, the air-fuel ratio G is calculated by dividing the air flow rate Ga by the fuel supply amount Gf.
Calculate a/Gf. In step 106, the air-fuel ratio G
By determining whether a/G f is greater than or equal to a predetermined value (for example, 200), it is determined whether the area is a region where inflammation is likely to occur. When the air-fuel ratio Ga/Gf is greater than or equal to the predetermined value, proceed to step 108), and the flame fluctuation information is set to the predetermined value ((3) above).
It is determined whether or not the occurrence of inflammation is predicted to occur by determining whether or not it is less than 90% (for example, 90% when formula is used, and 10% or less when formula (4) is used). When the judgment in step 108 is affirmative, it is predicted that the flame will be extinguished, so in step 110 the minimum fuel supply amount Gfm
Increase in by a predetermined value ε. On the other hand, when the air-fuel ratio Ga/Gf is less than the predetermined value or the flame fluctuation information exceeds the predetermined value, the generation of flame is not predicted, so step 112
The fuel consumption amount is reduced by reducing the minimum fuel supply amount Gfmin by a predetermined value ε.

Even when a microcomputer is used to predict and determine the occurrence of flame extinction, a gate circuit may be provided in the same manner as described above, and flame extinction may be predicted and determined based only on the signal that has passed through the gate circuit.

In addition, although the present invention was applied to a gas turbine engine equipped with a heat exchanger in the above, the present invention can also be applied to a gas turbine engine not equipped with a heat exchanger. Further, in the above description, the minimum fuel supply amount is increased to prevent the occurrence of flame-out, but the fuel supply amount Gf may be increased to prevent the occurrence of flame-out.

In the above, the air-fuel ratio Ga/Gf is defined as the fuel supply amount G
Although the configuration for calculating from each sensor output of f and air supply amount Ga has been described, as shown in FIG. /F may also be detected.

[Brief explanation of drawings]

1 and 2 are block diagrams for explaining the present invention, FIG. 3 is a block diagram of an embodiment of the present invention, FIG. 4 is a sectional view of a combustor of an embodiment of the present invention, and FIG. 5 Figure 6 is a diagram for explaining flame fluctuation information, Figure 7 is a diagram showing the relationship between air-fuel ratio and flame fluctuation information, and Figure 8 is a diagram when the temperature of the air at the combustor inlet is constant. Figure 9 is a diagram showing the relationship between the fuel flow rate and air flow rate when the temperature of the air at the combustor inlet is constant. A flowchart showing a minimum fuel supply amount calculation routine according to another embodiment of the present invention, and FIG. 11 is a block diagram of a modification of the present embodiment. 30...Compressor, 32...Turbine, 38...Combustor, 40...Sensor, 42...Heat exchanger.

Claims (1)

[Claims] (1) a flame detection means for detecting light generated from a flame in a combustor; a frequency analysis means for frequency-analyzing the signal output from the flame detection means to obtain a power spectrum; A flame fluctuation calculating means for calculating flame fluctuation information corresponding to the fluctuation; an air-fuel ratio detecting means for detecting an air-fuel ratio; and a flame-extinguishing prediction determining means for predicting and determining the occurrence of extinguishing based on the air-fuel ratio and the flame fluctuation information. A gas turbine engine flame-extinguishing prediction and determination device comprising: